A need exists for a rotomolded tank has with tolerance for apertures.
A further need exists for a rotomolded tanks that does not crack when such apertures are made or inserted into such tanks.
The present embodiments meet these needs.
The present invention relates generally to containers such as tanks for industrial processes and storage of liquids and solids, more particularly to a container with rotomolded components or flat sheet joined to an extruded cylinder.
After the oil strike in Titusville, Pa., the petrochemical and water industries have sought containers and tanks to store various fluids, slurries, gases, pellets, and solids. Such tanks have used reinforced concrete and steel observed at refineries, chemical plants, water treatment plants, factories, sewer plants, shipyards, terminals, and the like. Where industry has to store a component or ingredients, tanks appear and stand duty.
Industry has made tanks by winding layers of material for a few decades in many countries. Polymer tanks come in many sizes for various applications. The tanks begin as an extruder emits a strip of heated polymer onto a rotating mold. The extruder emits the strip under a roller gang that presses the polymer upon the mold. Following the first revolution of the mold, the extruder overlaps a new strip upon the adjacent previous strip as the extruder moves axially parallel to the mold. The extruder, roller gang, and mold cooperate to fuse the layers of polymer into a cylinder such as a tank.
Select tanks have had reinforcement with polymers like polyethylene, polypropylene, polyester, vinyl ester, epoxies of glass, carbon fiber, Kevlar®, and the like. The reinforcement enters the tank assembly as another component blended into molten polymer. However, select components alter the performance of the polymer and discourage mixing of them.
During extrusion of a tank, the strip has a width from a few inches to a foot and a thickness of ¼ to ½ inch. The strip wraps upon a rotating drum whose rotation slow ejects a nascent cylinder following compression by the roller gang. The roller gang compresses the polymer strip so that adjacent wrapped strips fuse totally and avoid any accumulation of air between adjacent strips. The strip has approximately ½ inch to half of strip width of overlap between adjacent wraps as the extruder moves horizontally and ejects a nascent cylinder. This wrapping of strip to form a cylinder appears similar to the medical practice of wrapping a bandage, or cast material, upon a human arm. Repeating the wrapping of the strip back and forth horizontally with the extruder then increases the wall thickness of a resulting polymer cylinder for a tank, a pipe, or when slit, a flat sheet.